Conventional lighting applications include not only a vehicle lighting but also a backlight for a display and a signage.
A light emitting device, for example, a light emitting diode (LED) has advantages such as low power consumption, semi-permanent lifetime, fast response speed, safety, environmental friendliness compared to conventional light sources such as fluorescent lamps and incandescent lamps. Such an LED has been applied to various lighting devices such as various display devices, indoor lights or outdoor lights, or the like.
Recently, a lamp employing an LED has been proposed as a vehicle light source. Compared to incandescent lamps, an LED has an advantage in low power consumption. However, since an emitting angle of light emitted from an LED is small, when the LED is used as a vehicle lamp, it is required to increase a light-emitting area of a lamp using the LED.
Since a size of an LED is small, it is possible to increase a degree of freedom of design of a lamp, and the LED has economic efficiency due to the semi-permanent lifetime.